Magnetic device



1959 TUNG- CHANG CHEN 2,918,663

MAGNETIC DEVICE Original Filed 001;. 2, 1953 INTERROGATE r63 INTERROGATEPULSE SOURCE 66- PULSE SOURCE SET SET SET 43 7 SET PULSE PULSE '65 pSOURCE SOURCE ss u E S C J L ISC E 64 1 2 OUTPUT FIG. 9 a FIG. 1 LOAD,4; EgKB 47 B SAT 6 42 ATTORNEY FIG 4 FIG? 1 FlG.l3

United States Patent MAGNETIC DEVICE Tung Chang Chen, Villanova, Pa.,Corporation, Detroit, Mich.,

Continuation of application Serial N 0. 383,801, October 2,

1953. This application June 10, 1959, Serial No. 819,451

assignor to Burroughs a coporation of Michi- 29 Claims. (Cl. 340174)This invention relates to information storage systems and moreparticularly to information storage systems utilizing magnetic cores.

The present application is a continuation of my earlier filed copendingapplication entitled Magnetic Device, Serial No. 383,801, filed October2, 1953, and now forfeited.

, In the computing art there are many types of storage withoutmaintenance of a constant power supply and unchanging characteristicswith use and age.

Some of the more recent storage devices utilizing mag netic materialscomprise magnetic cores, especially, but not necessarily, magnetic coresof an annular or toroidal shape.

This invention involves the sensing of information stored in the form ofremanent magnetic states of a core in a manner which does not destroysuch remanent state and, hence, permits repeated sensing and use of thesame information. According to one aspect of this invention,non-destructive sensing is accomplished in a toroidal core by passingelectrical current through the core in a direction transverse to thedirection of the remanent flux, so as to create a detectable flux changewithin the core without destroying its remanent state. The flux changethus produced is detected by a winding wound about the entirecross-section of the core at a point remote from the region of thetransverse current flow, such winding developing an outputvoltage'indicative of the sense of the remanent state. In one embodimentof the invention, to be discussed, the flux change within the core isproduced by applying a signal to a conductor passed through twoapertures in the toroidal core so as to encircle the region between theapertures. This is an improvement upon the magnetic core device shown ina co-pending application entitled Magnetic Device, Serial No. 248,- 716,filed September 28, 1951 by Joseph Chedaker, George G. Hoberg and EugeneA. Sands, and assigned to the assignee ofthe present application.According to another aspect of the invention, non-destructive sensing isachieved by the use of just two apertures in a solid magnetic core inwhich the magnetic material in the region between the two apertures isset into one remanent state or the other by means of a conductor passingthrough one of the apertures and the state of the core is sensed bymeans of an interrogation winding passing through the other aperture.This core preferably takes the form of a loop of magnetic materialhaving a single aperture passing through the magnetic material of theloop in a direction transverse to. that of the remanent 2,918,663Patented Dec. 22, 1959 flux within such loop. A signal is applied to aconductor passing through this single aperture for creating anondestructive flux change within the loop and this flux change isdetected by an output winding coupled to the loop.

More specifically, one embodiment of the invention comprises a closedtoroidal core of magnetic material having a pair of closely spacedapertures therethrough, such spacing being relatively close with respectto the mean circumference of the core. A first winding means is woundthrough these apertures which, when energized, generates magnetic fluxin the core. tion of this flux, throughout the interval of suchenergization, cannot be fixed with certainty, it is believed some suchflux remains localized around said apertures while a significant portionof it passes around the entire length of the core. Energizing means isprovided to cause the core to become saturated with magnetic flux in onep0- larity so as to produce a remanent magnetic field of that polarity.A second energizing means is provided to cause the core to becomesaturated with magnetic flux of an other polarity so as to produce aremanent magnetic field of said other polarity. A second winding meansis wound around said core remote from said apertures to detect a signaloutput produced upon energization of the first winding means, whichoutput is indicative of the remanent state of the core.

Another embodiment of the invention comprises a closed loop or core ofmagnetic material having just a single aperture therein. A first windingmeans is wound through the single core aperture and around the edge ofsaid loop of magnetic material. Energization of said first winding meanswill cause a substantial amount of magnetic fiux to be created about theentire core when such core is magnetized in one magnetic remanent stateof one polarity but a significantly lesser amount of flux about suchcore when it is in a magnetic remanent of the opposite polarity. A firstmeans is adapted to cause the loop of magnetic material to becomesaturated with magnetic flux of a first polarity to produce a firstremanent state, and a second means is adapted to cause the said loop ofmagnetic material to become saturated with magnetic flux of a secondpolarity to produce a second remanent state. A second winding means iswound around said loop of magnetic material and is adapted to detectoutput signals produced upon energization of the first winding means.

In accordance with one feature of the invention, the said second windingmeans of said first embodiment of the invention has connected in seriestherewith a resistive means, and connected across the series combinationof said second Winding means and said resistive means is anasymmetrically conducting device.

In accordance with another feature, the second embodiment of theinvention has a resistive means connected across the said second windingmeans.

These and other objects and features of the invention will be more fullyunderstood from the following detailed description when read inconjunction with the drawings, in which:

Fig. 1 is a schematic view of one embodiment of the invention;

Fig. 2A illustrates a portion of Fig. 1 to show the magnetic fluxdistribution which is believed to be produced in core 20 by theenergization of the winding 22 when the core is in a clockwise orpositive magnetic remanence condition;

Fig. 2B shows the fiux distribution thus produced when the core is in acounterclockwise or negative magnetic.

Although the exact distribuof Fig. 1 which is caused by said firstenergizing means and the effect, on this magnetic flux which is believedto be produced by said first winding means;

Fig. 4 shows a curve of the output of said second winding means underthe positive remanent conditions shown in Fig. 3; i

Fig. 5 shows a curve of the output of said second winding means of thestructure of Fig. 1 under the conditions of Fig. 3 when anasymmetrically conducting device is connected across the terminals ofsaid second winding means;

' Fig. 6 shows a curve of the negative remanent magnetic flux around thesaid toroidal loop of magnetic material caused by said second energizingmeans and the effect on this magnetic flux which is believed to beproduced by said first winding means; l A

Fig. 7 shows a curve of theoutput of said second winding means under thenegative remanent conditions showninrig'e; J

"Fig. 8' shows a curve of the output of said second winding means of thestructure of Fig. 1 under the conditions ofFig. 6 when an asymmetricallyconducting device is connected across the terminals of said secondwinding means of said first embodiment;

Fig. 9 is a schematic sketch of a second embodiment of the invention; '1

Fig. 10 is an illustration of a portion of Fig. 9 to show the magneticflux distribution believed to be produced in core '41 by theenergization of winding 42 when the coil is in a positive remanent fluxcondition;

Fig. 11 is an illustration of the same portion of Fig. 9 to show theflux distribution upon energization of winding 42 when the core is in anegative remanent flux condition;

Fig. 12 shows the output from the output winding means of Fig. 9 for thepositive remanent condition;

Fig. 13 shows the output from the output winding of Fig. 9 for thenegative remanent condition; and

Fig. 14 shows the'hysteresis loop of the core material forming the coresof Figs. 1 and 9.

Preliminary to a detailed discussion of Figs. 1 and 9, it may be well todiscuss very briefly the operation of the magnetic core material used inthe cores of these figures in terms of their hysteresis loop shown inFig. 14. in this figure the various flux density conditions B of themagnetic core material are plotted against the applied magnetizingforces H which produce these conditions. After'the material has beensaturated repeatedly first in one direction and then in the oppositedirection, it will tend to follow a curve such as that shown in Fig. 14wherein with no applied magnetizing force (H=O) the core will remain atfiux density condition Br or Br depending upon the polarity of the lastapplied magnetizing force. These points Br and Br are called positiveand negative remanent flux density states, respectively.

If the core is at point Br when a positive magnetizing force is applied,it will traverse the hysteresis loop toward positive flux saturation (Bsat), and will reach this point if the magnetizing force is, sufficient.Thereafter, upon removal of this force, the core material will continuealong the loop to settle at point Br. Likewise, if the core is at pointBr when a negative magnetizing force of suflicient magnitude is applied,it will traverse the loop to negative flux saturation (B sat.) and, uponremoval of this force, will settle at point Br. The state of the core inthese cases is said to switch'from Br to Br or vice versa.

Qnthe other. hand, if the core is at positive remanence Br whenapositive magnetizing force is applied, it will merely traverse thehysteresis loop to point B sat., and upon remo val of this. magneticforce, return toBr. And, lil ewiseif itis at negative remanence Br. whena negative magnetizing force is applied, it will merelytravel. to pointB sat. and, upon removal of the force, return to Br. The state of thecore under such circumstances is often said to be non-switchable withrespect to the applied force, since the force is not in a direction toswitch the core from positive to negative remanence or vice versa.

it will be seen that the amount of flux change in the non-switchablecore (i.e. B sat.Br or B sat.Br) is small in comparison with the fluxchange produced when the material is in a switchable state (i.e. Bsat-Br or B sat.Br). This is especially true where the hysteresis loopof the core is rectangular, i.e., where the Br to B sat. ratio isrelatively close to unity. Indeed for the hypothetical case of a corehaving perfectly rectangular hysteresis loop, where Br equals B sat.,the flux change for a nonswitchable core would be zero.

Referring now to the embodiment of the invention illustrated in Fig, 1,core 20 is of a material preferably having a substantially rectangularhysteresis loop characteristic as shown in Fig. 14, this shape of loop,while substantially rectangular, being characterized by an appreciableand readily detectable flux change between remanence and saturation. Thecore is provided with a pair of apertures 23 and 24 which are relativelyclosely spaced as shown and provide a means whereby a winding 22 may bewound therethrough. When energized by a pulse from the interrogate pulsesource 63, the wind ing 22 will cause a magnetic flux to be formed aswill be explained. A set winding 26 is wound around the core 20 and whenenergized by a set pulse source 64 connected across it will cause themagnetic core 20 to be driven towards clockwise or positive magneticflux saturation so as to produce positive remanence Br, shown by arrow55. A reset winding 27 is wound around the core 20 and when energized bya reset pulse source connected thereacross it will cause the magneticcore 20 to be driven towards counterclockwise or negative magnetic fluxsaturation so as to produce negative remanence Br, as shown by arrow 56.An output winding 28 is also wound on the core 20, remote from apertures23 and 24. Connected in series with the output winding 28 is aresistance 29 and an output load 70. Diode 30 is connected across theoutput load and performs the functions of permitting a current of onepolarity only to flow through the output load 70.

In one preferred embodiment of the invention the following values andmaterials may be used. The magnetic core 20 may be of a ferrite materialor any other magnetic material having a hysteresis characteristic shapedas shown in Fig. 14. The magnetic core has an outer diameter of .88inch, awidth of .19 inch, and a thickness of .13 inch. The apertures 23and 24 have diameters of .06 inch and are spaced about .08 inch apartfrom center to center. The centers of the apertures 23 and 24 are on themean diameter of the core. Winding 22 has 5 turns, set winding 26 has 50turns, reset winding 27 has 50 turns, and output winding 28 has 50turns. Resistance 29 has a value of 220 ohms. It is to be noted thatother values of circuit constants and other materials, sizes, and shapescan be used in the invention to conform to particular design needs.

Referring now to Fig. 9, the magnetic loop or core 41 has a singleaperture 43 therein which divides the core at that point into twoseparate paths 6 and 7. Winding 42 is wound through said aperture andabout the edge of the core so that, when energized by interrogate pulsesource 66, it will generate a magnetic flux in path 6. Set winding 44 iswound on the core 41 and has its terminals connected to set pulse source68. Reset winding 45 is wound on core 41 and has its terminals connectedto thereset pulse source 67. Also wound on. the core 41 is outputwinding 46, the terminals of which are connected to output load 69.Resistance 47 is connected across the output load 69.

In one particular embodiment of the invention shown in Fig. 9, thefollowing values maybe used. Thedimensions and material of. the magneticcore 41 are the same as for core 20 of Fig. 1. The single aperture 43has a ammonia the-set winding 4-4has '50 .turns, the reset winding has50 turns, and the output winding 46 has 50 turns. The resistor 47 has avalue of 220 ohms. It is to be noted that other circuit values,materials, sizes and shapes may be used inaccordance with particulardesign needs.

Referring again to Fig. 1 the'operation thereof will be described indetail. As noted above, energization of the set winding 26 will, uponcessation of the energizing pulse, leave the core 20 in a remanent fluxcondition of positive polarity, as indicated by arrow-55, whileenergization of the reset winding 27 will, upon cessation of theenergizing pulse, leave the core 20 to acquirea remanent magnetic fluxof a negative polarity, :as indicated by arrow 56. By energizing winding22 the polarity of the output pulse thereby produced in winding 28, andits amplitude when diode 30 is employed, will indicate the core remanentstate. This can --be seen from .Figs. 2A and 2B, considered inconnection with Figs. 3 to8. In Figs. 2A and 2B the paths onoppositesides of apertures 23 and 24 have, for convenience, been designated 1,2, 3 and 4.

Consider first Fig. 2A, which illustrates core 20 being in a positiveremanent state, as shown by arrow 55. Upon energizationof winding 22 byan applied pulse, some flux will tend to flow locally around "apertures23 and 24, as shown by arrows 100, 101, 102 and 103. Paths 1 and 4 willpresent-a relatively low reluctance to such flux while paths 2 and -3will present a relatively high reluctance. The reason for'this is thatwith core 20 in a positive remanent state paths 1 and 4'are magnetizedin a direction opposite to that of the localized flux in those paths andhence areswitchable while paths 2 and 3 are magnetized in the samedirection as such local flux and hence are non-switchable. Thenon-switchable paths, as noted above,'permit 'verylittle flux changetherein and hence are high reluctance paths. Otherwise stated, the easypath is in a direction opposite to that of the remanent flux. Since path1 presents a considerably lower reluctance than: path 3, point X, whichis marked on core 20, is at a much highermagnetomotive force level thanpoint Y, the flux starting at winding 22 having traversed a lowreluctancepath lto reach point X while having traversed high-reluctancepath 3 to reach ,point Y. As a'consequence of this difference in mmflevel, .a substantial amount of flux from winding 22 will pass frompoint -X to point Y in a counterclockwise direction around the entirecore to produce an output voltage on winding 28 (Fig. 1).

An alternative way of viewing the basis for the flux distributionproduced by the energization of winding 22 is that a substantial amountof flux produced by winding 22 will pass through path 1, since that pathis switchable, but that very little of this flux can return to winding22 viapath 2 since such path is non-switchable, hence the remainderofsuch flux-returns via a path around the entire core 20.

The operation of Fig. 2B is similar. Here core 20 is in a negativeremanentstate 56. As a result, paths 2 and 3 are switchable and hencelow reluctance to the flux produced by winding 22 while paths 1 and4non-switchable and high reluctance thereto. The -M.M.F. level of pointY, therefore, will be higher than that of point X and hence asubstantial amount of flux willpass clockwise around the entire core 20to producean output pulse in winding 28 (Fig. 1).

Fig. 3 shows a plot of the magnetic flux in the core 20 versus time whenthe core is in a positiveremanent flux condition, as in Fig. 2A, and apulse is applied to the winding 22. The dip 70 appearing in the curve 31of Fig. 3 shows the flux which would be produced by winding 22 if diode30 were not present, which flux, as noted, passes counterclockwiseabout-core 20 in a direction opposite to that of the positiveremanentfiux. Fig. 4 shows re the voltage which would be generated atthe terminal 57 ofatnebutput winding=28=if diode 30 were not present.

Fig. 5-.shows the output voltage appearing across the terminals 57 whenthe-diode is'present, as is shown under the actual circuit conditions ofFig. 1. Fig. 5 shows that whenthe core 20 has a positive remanentfluxcondition asin 'Fig. 2A, and a pulseis caused to be passed.throughwinding 22, the loading ofthe resistance 29 and the asymmetricaldevice 30 prevents any substantial change of magnetic flux in the corein the direction to reduce the level of the residual flux 5 .(Fig. 3)and therefore there is -no reverse change caused by the flux retumingtothis level. The output signal, as is shown in Fig. 5, is small as aresult ofthis limiting of the flux change and also because the negativevoltage induced in winding 28 will be shorted out by the low forwardimpedance of theasymmetrical device 30.

:Fig. 6 shows a plot of themagnetic flux in thecore 20 versus time whenthe core has a negative remanent-flux condition, as in Fig. 2B, and apulse is applied to the winding 22. The rise 71 in curve 32 shows theflux produced by winding 22 which passes clockwise around the coreinadirection opposite to'that of the negative remanent flux. Fig. 7 showsthe output voltage induced acrossthe output terminals 57 of outputwinding 28 by such flux, assuming the diode 30 not to be present. Fig. 8shows the voltage-thus induced across the output terminals 57 whenthediode is present, as is shown under the actual circuit conditions ofFig. 1. The diode 30 and the resistor 29 act as a load on the core 20when the mag netic flux ischanged in onedirection, but have practicallyno effect when the magnetic flux changes in the opposite direction. Thisis shown in Fig. 8. The output signals shown in Figs. 4 and 7, which aredistinguishable on a phase or polarity basis, have thus been rendereddistinguishable from each other on an amplitude basis, as shown by Figs.5 and 8, by means of the asymmetrical device 30 which will permitcurrent to flow therethrough in one direction only.

Referring'now to Fig. 9, the operation of the circuit shown therein willbe described in detail. A pulse of current may be impressed upon eitherthe terminals of the set winding 44 to cause the magnetic core 41tobecome positively saturated with magnetic flux or upon the terminals ofthe reset winding 45 'to cause the magnetic core 41 to become negativelysaturated with magnetic flux. After cessation of the pulse the core 41is left in a positive or negative remanent condition. If theinterrogation winding 42 is then pulsed, the presence or absence of apulse on winding 46 will be indicative of the core remanent state.

in Fig. 10, in which a portion of core 41 of Fig. 9 is shown, theremanent state of the core is positive, as shown by arrow 58. Whenwinding 42 of this figure is energized a flux is produced in path 6 ofthe core which tends to flow in the direction of arrows 59. It can beseen that the magnetic flux thus generated will have a large reluctance.presented thereto by the path extending around the entire magnetic core41 but will have a comparatively low reluctance presented thereto bypath 7 adjacent aperture 43. The difference in the reluctance of thesepaths is the result of two factors: firstly, the path around the entirecore is longer than path 7 and, secondly, such path is non-switchablewhile path 7 is switchable. Path 7 thus forms a magnetic shunt for fluxproduced in path 6 by winding 42 so as to shunt such flux away from thepath around the entire core.

Consequently, most of the magnetic flux generated by the winding 42flows immediately around the aperture 43. Moreover, the total amount offlux generated by winding 42 will be small since path 6 isnon-switchable. (No flux at all will be generated if the hysteresis loopof the core is prefectly rectangular.) The net elfect of these factorsis that very little flux change will occur around relatively lowreluctance presented to it by the magnetic path extending around theentire loop 41, since this path is now switchable, while path 7 willhave a relatively high reluctance, since this path is nownon-switchable. -1sequently, most of the flux produced by winding 42will "pass around the entire core. Moreover, the total amount Conof fluxgenerated by this winding will be relatively large since path 6 isswitchable. Because of these factors, there will be a very appreciableflux change about the entire magnetic loop 41. This change in flux willbe detected by the output winding 46 (of Fig. 9) and will induce a veryappreciable voltage in that winding, as is shown in Fig. 12.

While an explanation has now been given of the flux distribution uponenergization of windings 22 and 42 in the cores of Figs. 1 and 9, whichcores are shown merely as illustrative embodiments of the presentinvention, this explanation is intended merely as an aid in theunderstanding of the operation of these cores. While this explanation isbased upon extensive tests made to determine the exact mode ofoperation, it is far easier to ascertain the flux distribution beforeand after energization of windings 22 and 42 on these cores, while thecores are in a remanent flux state, than to fix the precise distributionfor the changing flux state during energization of these windings, and,therefore, the precise distribution of this changing flux has not beenascertained with any real degree of certainty. Nevertheless, it iscertain that energization of windings 22 and 42 of these cores producesthe described output voltages which are indicative of the core remanentstate. This being so, shortcomings in the theoretical explanation, ifthere be any, will not detract from the advantages of the presentinvention.

It is to be noted that the embodiments of the invention herein shown anddescribed are but preferred embodiments of the same and that variouschanges may be made in materials, uses, sizes, circuit constants andcircuit arrangements without departing from the spirit or scope of theinvention.

What I claim is:

l. A magnetic storage device comprising a closed loop of magneticmaterial capable of assuming either of two magnetic remanent storagestates, said loop of magnetic material having a first aperturetherethrough and a second aperture therethrough spaced relatively closetogether with respect to the size of said loop of magnetic material,first winding means wound through said first and second apertures forproducing a magnetic flux change in said closed loop of magneticmaterial indicative of the storage state thereof, a second winding meanswound around said closed loop of magnetic material for placing saidmagnetic material in one of its remanent storage states, a third windingmeans wound around said loop of magnetic material for placing saidmagnetic material in the other of its remanent storage states, and afourth winding means responsive to the magnetic flux change produced bysaid first winding means wound around said loop of magnetic material, aresistance connected in series with said fourth winding means, and anasymmetrically conducting device connected across said seriescombination of said fourth winding means and said resistance, and loadmeans connected across said asymmetrically conducting device.

2. A magnetic storage device comprising a closed loop of magneticmaterial capable of assuming either of two magnetic remanent storagestates, said loop of magnetic material having a first aperture thereinand a second aperture therein, a first means to cause substantialmagnetic saturation of said loop of magnetic material in a firstpolarity to produce one of said remanent storage states, a second meansto cause substantial magnetic saturation of said closed loop in a secondpolarity to produce the other of said remanent storage states, a firstwinding means wound through said first and second apertures for creatinga magnetic flux change in said closed loop indicative of the remanentstorage state thereof, a second winding means responsive to the fluxchange produced by said first winding means wound around said loop ofmagnetic material for producing an output voltage indicative of theremanent storage state of said loop, a resistance means connected inseries with said second winding means, and a diode means connectedacross said series combination of said second winding means and saidresistance.

3. A magnetic storage device in accordance with claim 2. furtherincluding means for energizing said first winding means to substantiallyincrease the magnetic reluctance to any magnetic flux flowing around thesaid loop of magnetic material when said first winding is energized, inwhich said first means comprises a third winding wound on said loop ofmagnetic material, and in which said second means comprises a fourthwinding means wound on said loop of magnetic material.

4. A magnetic storage device comprising a closed loop of magneticmaterial capable of assuming either of two magnetic remanent storagestates, a first aperture through said loop of magnetic material, asecond aperture through said loop of magnetic material, a first windingmeans wound through said first and second apertures for producing amagnetic flux change in said closed loop indicative of the storage stateof said loop, said first and second apertures and said first windingmeans being adapted to substantially increase the reluctance to anymagnetic flux flowing around the said loop of magnetic material, a firstmeans to cause said loop of magnetic material to become saturated withmagnetic flux of a first polarity to produce one of said remanentstorage states, a second means to cause said loop of magnetic materialto become saturated with magnetic flux of a second polarity .to producethe other of said remanent storage states, and a second winding meansresponsive to the magnetic flux change produced by said first windingmeans wound on said loop of magnetic material, a resistive meansconnected in series with said second winding, and a diode meansconnected across the series combination of said second winding means andsaid resistance.

5. A magnetic storage device comprising a closed loop of magneticmaterial capable of assuming either of two magnetic remanent storagestates, said loop of magnetic material having an aperture therein, afirst winding means wound through said aperture and around at least oneedge of said loop of magnetic material for producing in said loop amagnetic flux change indicative of the stor age state of said loop, afirst means adapted to cause said loop of magnetic material to becomesaturated in a first polarity to produce one of said remanent storagestates, a second means adapted to cause said loop of mag netic materialto become saturated in a second polarity to produce the other of saidremanent storage states, a second winding means responsive to themagnetic flux change produced by said first winding means wound on saidloop of magnetic material, and a resistive means connected in serieswith said second winding means.

6. A magnetic storage device in accordance with claim 5 comprising afirst energizing source adapted to energize said first winding means, inwhich said first means comprises a third winding wound around said core,and a second energizing means to energize said third winding, in whichsaid second means comprises a fourth winding wound around said core, anda third energizing means to energize said fourth Winding.

7. A magnetic storage device comprising an annularly shaped core ofmagnetizable material and capable of assuming stable remanent magneticstates, a first means for creating a magnetic flux completely around thecore in one direction of polarity, a second means for creating amagnetic flux completely around the core in the opposite direction of.polarity,-said core having a single aperture only through aportion ofthe core between the inner and outer radial: dimensions thereof, aWinding extending through said aperture and encircling a part of thecore so that when energized the magnetic field created thereby will aidthe magnetic flux created by said first means, and will oppose themagnetic flux created by said second means.

8. A magnetic storage devicecomprising aclosed continuous-toroidal coreof magnetic material capable of assuming either of two magnetic remanentstorage states and providing a main magnetic flux-path along a firstportion of itslength, said core having at least one aperture through itsmagnetic material along-a second portion of its length for providing twoseparate branch paths along saidsecond portion, one on each side of saidat least one aperture magnetizing means including an input windingpositioned in electromagnetic coupling arrangement -to said core formagnetizing sa-id core in one-or the other of said remanent storagestates, an interrogating winding passing through said at least oneaperture for creating a changeinmagnetic flux in said core indicative ofthe magnetic storage state of the core, and an output windingpositionedaboutsaid first portion of the core-for detecting flux changesin said first portion produced by said interrogating winding.

9. A magnetic storage device comprising a toroidal core of magneticmaterial capable of assuming a first remanent storage state of magneticfiux polarization in one-sense about said core and a second remanentstorage state of magnetic flux polarization in the opposite senseabout-said core, said core having at least one aperture through itsmagnetic material in a direction transverse to said flux polarizationsenses, magnetizing means includingan'input'winding positioned'inelectromagnetic coupl-ingmelation'to saidcore for'magnetizing said corein either said one sense or said opposite sense to produce said first orsecond remanent storage states, interrogating means :for determining thestate ofsaid core including a windingpassing through said at least oneaperture for creating in said core a magnetic flux the major portion ofwhich passes around the entire core body in said one sense only-when-thecore is in its second remanent storage state'of magnetic polarization inthe'opposite sense, and an output winding coupled to said core fordetecting said magnetic flux to produce an output voltage indicative ofthe core storage state.

10. A magnetic storage device as'called for in claim 9 wherein said corehas apair of apertures through its magnetic material through whichtheinterrogating winding passes.

1 1. :A magnetic' storage device comprising an annularly shaped core ofmagnetic material capable of assuming either of two storage states ofmagnetic remanence, said-annular core having at least one aperturethrough its magnetic material in a direction transverse to thedirections of-fiux in said two remanent storage states, magnetizingmeans including an input winding positioned in'electromagneticcouplingrelation to said core for magnetizing said core in one or theother of its remanent storage states, an interrogating-winding passingthrough said atleast one aperture for producing an interrogating fluxchange in said annular core indicative of the storage state of saidcore, and an output winding positioned about a non-apertured portionofsaid core for detecting flux changes therein causedby'saidinterrogating winding.

1-2.'A magnetic storage device as called for in claim '1 1"whereinsaidannular core has a pair of apertures through its'ma'gnetic materialthrough which the interrogating winding passes and which furtherincludes an asymmetrical conducting device connected to at least oneterminal of the output winding.

13. A magnetic storage device as called for in claim 11 10 wherein saidat least one aperture extends entirely through saidcore body in adirection substantially parallel to the axis ofsaid annularly shapedcore.

14. A magnetic storage device comprising an annularly shapedcoreofmagnetic material capable of assuming a first and second storagestateof magnetic remanence, said core having but asingle aperturethroughits magnetic material in a direction transverse to the directions offlux in said first and second remanent storage states, magnetizing meansincluding at least one input winding positioned in electromagneticcoupling relation to said core for magnetizing said core in one or theother of said remanent storage states, an interrogating winding passingthrough said singleaperture for creating a change in flux in said coreindicative of the storage state thereof, and an output Windingpositioned about a'non-apertured portion of said core for detecting theflux change therein caused by said interrogating winding.

15. A magnetic storage device comprising an annularly shaped core ofmagnetizable material capable of-assuming magnetic remanent storagestates of opposite polarities, a first means for creating a magneticflux completely around the core in one polarity or completely around thecore in the opposite polarity for establishing in the core said magneticremanent storage-states, said core'having a single aperture only througha portion of the core between the inner and outer radial dimensionsthereof, a Winding extending through said aperture for creating, whenenergized, a magnetic flux in said core which passes around theentirecore body in one polarity only when the core is in its-remanentstorage state of opposite polarity.

16. A magnetic storage device comprising an annularly shaped core ofmagnetizable material capable of assuming magnetic remanent'storagestates of opposite polarities, a first means for creating a magneticflux completely around the core-in one polarity or completely around thecore in the opposite polarity'for establishing in the core said magneticremanent storage states, said core having an aperture through a portionof the core between theinner and outer radial dimensions thereof, awinding extending through said aperture for creating, when energized, amagnetic flux in said core which passes around the entire core body inone polarity only when the core is in its remanent storage state ofopposite polarity, and winding means positioned about a non-aperturedportion of-said core for detecting flux changes about the entire corebody.

17. A magnetic device comprising a closed toroidal core of magneticmaterial capable of assuming first and second .remanentflux states, atleast one pair of apertures through said toroidal core, a plurality ofwindings each coupled electromagnetically to at least a portion of saidcore, one of said windings passing through said pair of apertures andhaving its axis perpendicular to the mean diameter of said core forproducing flux in a localized ,path within said core, at least one otherwinding wound about the entire cross-section of the core along anon-apertured portionof its length.

18. A magnetic storage device comprising a closed annular loop ofmagnetic material capable of assuming magnetic remanent storage statesof two polarities, a first aperture through said loop of magneticmaterial, a second aperture through said loop of magnetic material,means to cause said loop of magnetic material to be saturated withmagnetic flux in a'first or second polarity, a first Winding means woundthrough said first and second apertures for creating, when energized, amagnetic flux in said loop which passes around the entire body of theloop in said first polarity only when said loop is in its secondpolarity remanent state, and a second winding means wound around anon-apertured portion of said loop of magnetic material and serving asan output for the device.

19. A magnetic storage device comprising a closed toroidal core ofmagnetic material capable of assuming either of two remanent fluxstates; a pair of apertures through said toroidal core; a plurality ofwinding means each coupled electromagnetically to at least a portion ofsaid core, a first of said winding means passing through said pair ofapertures and surrounding the core region between said apertures forproducing therein a flux in one polarity, the other of said windingmeans being wound about the entire cross section of said toroidal corealong the non-apertured portion of its length for producing fluxencircling said entire toroidal core in one polarity or another, saidencircling flux passing through the region between said pair ofapertures so as to loop but one aperture of said pair; and meansassociated with one of said Winding means for producing a signal whosepolarity is dependent upon the relative polarities of the flux producedby said first and said other winding means.

20. A magnetic core storage device comprising a closed substantiallytoroidally shaped core of magnetic material capable of assuming eitherof two remanent flux states; a pair of apertures through said core onsubstantially the mean diameter of the core and extending generallyparallel to the axis thereof; a plurality of winding means each coupledelectromagnetically to at least a portion of said core, a first of saidwinding means passing through said pair of apertures and surrounding thecore region between said apertures for producing therein a fluxextending perpendicular to and intersecting the mean diameter of thecore, other of said winding means being wound about the entire crosssection of said toroidal core along a non-apertured portion of itslength and operable to produce a magnetic flux encircling said entirecore in one polarity or the other; and means connected to one of saidwinding means for producing a signal whose polarity is dependent uponthe relative polarities of the fiux produced by said first and saidother winding means.

21. A magnetic storage device comprising a closed toroidal core ofmagnetic material capable of assuming either of two remanent fluxstates; an aperture through said toroidal core in a direction transverseto the directions of flux in said two remanent flux storage states; aplurality of winding means each coupled electromagnetically to at leasta portion of said core, a first of said winding means passing throughsaid aperture and about an edge of said core for producing a flux in thecore region between said aperture and said edge, other of said windingmeans being wound about the entire cross section of said toroidal corealong the non-apertured portion of its length for producing a flux ofone polarity or the other encircling said entire toroidal core, saidencircling fiux passing through the region between said edge and saidaperture in a polarity opposite to that of the flux produced by saidfirst winding means; and means associated with one of said winding meansfor producing a signal indicative of the relative polarities of the fluxproduced by said first and said other winding means.

22. A magnetic storage device comprising an annularly shaped loop ofmagnetic material capable of assuming eithera first or a second magneticremanent state, said states being of opposite polarities; a firstaperture through said loop of magnetic material; a second aperturethrough said loop of magnetic material; a first winding means woundthrough said first and second apertures, said first winding means inresponse to current flow therethrough substantially increasing thereluctance to any magnetic flux flowing around said loop of magneticmaterial; input current means magnetically coupled to said loop ofmagnetic material for causing said loop to assume one or the other ofsaid first or second states of magnetic remanence; and a second windingmeans wound around a non-apertured portion of said loop of magneticmaterial and serving as an output for the device.

23. A magnetic device comprising a toroidal core of magnetic materialcapable of assuming stable remanent magnetic states, magnetizing meansincluding a winding positioned in electromagnetic coupling arrangementto said core for magnetizing said core in alternate ones of saidremanent states, said core having an aperture passing through its bodytransversely to the direction of the magnetic flux in said alternateremanent states, means including a conductor passing through saidaperture for producing an alteration in the magnetic reluctance of alocalized portion of said core, and an output winding wound about anon-apertured portion of said core and responsive to the flux changeproduced in said core by said reluctance alternating means for producingan output voltage indicative of the core remanent state.

24. A magnetic device according to claim 23 wherein said aperturedivides the cross section of the core into two substantially equalportions.

25. A magnetic device comprising a toroidal core of magnetic materialcapable of assuming stable remanent magnetic states, magnetizing meansincluding a winding positioned in electromagnetic coupling arrangementto said core for magnetizing said core in alternate ones of saidremanent states, means for passing electrical current flow through thebody of said core which lies between its inner and outer toroidalperipheries at a localized portion thereof and in a direction transverseto the directions of flux of said alternate remanent states, and anoutput winding positioned about said core at a point remote from saidlocalized portion and responsive to the magnetic flux change produced insaid core by said electrical current fiow for producing an outputvoltage indicative of the core remanent state.

26. A magnetic device comprising a toroidal core of magnetic materialcapable of assuming stable remanent magnetic states, magnetizing meansincluding a winding positioned in electromagnetic coupling arrangementto said core for magnetizing said core in alternate ones of saidremanent states, conductive means extending through the body of saidcore which lies between its inner and outer toroidal peripheries in adirection transverse to the directions of flux of said alternateremanent states at least in a localized portion of said core for passingelectrical current flow transversely through said core in said localizedportion, and an output winding positioned about said core at a pointremote from said localized portion of the core and responsive to themagnetic flux change produced in said core by said electrical currentfiow for producing an output voltage indicative of the core remanentstate.

27. A magnetic device comprising a loop of magnetic material which iscapable of assuming stable states of magnetic remanence, said loophaving just a single aperture through the magnetic material between itsinner and outer peripheral boundaries in a direction transverse to thedirections of flux in said stable remanent states, magnetizing meansincluding at least one winding positioned in electromagnetic couplingrelation to said loop for magnetizing said loop in one or the other ofsaid stable remanent states, an interrogating winding passes throughsaid single aperture for creating a flux change in said loop indicativeof the remanent state thereof, and an output winding in electromagneticcoupling relation to said loop for detecting the flux change causedtherein by said interrogating winding.

28. A magnetic core device comprising a core of magnetic material whichis capable of assuming stable states of magnetic remanence, such corehaving just two apertures therethrough and including at least a firstclosed magnetic path formed by the magnetic core material surroundingone of said apertures and at least a second magnetic path formed by themagnetic core material surrounding the other of said apertures, saidfirst and second closed magnetic paths being common for a portion oftheir respective lengths, winding means including a conductor passingthrough one of said apertures for magnetizing said common portion in onedirection or the other to produce a remanent flux state in said commonportion in one direction or the other, interrogate winding meansincluding a conductor passing through the other of said apertures forcreating a flux change in said common portion having a magnitudedependent upon the direction of said remanent flux state in said commonportion, and output circuit means including a second conductor passingthrough said one aperture for detecting the flux change produced by saidwinding means in said common portion.

29. A magnetic core device comprising a core of magnetic material whichis capable of assuming stable states of magnetic remanence, such corehaving just two apertures therethrough and such apertures being spacedapart to form a common magnetic branch path therebetween, winding meansincluding a conductor passing through one of said apertures formagnetizing said common branch path in one direction or the other toproduce a remanent flux state in one direction or the other, interrogatewinding means including a conductor passing References Cited in the fileof this patent UNITED STATES PATENTS 2,652,501 Wilson Sept. 15, 19532,673,337 Avery Mar. 23, 1954 2,708,219 Carver May 10, 1955 2,736,880Forrester Feb. 28, 1956 2,741,757 Devol et a1 Apr. 10, 1956 FOREIGNPATENTS 881,089 Germany June 25, 1953 OTHER REFERENCES Proceedings ofAssoc. for Comp. Mach., May 1952, pp. 223-229.

Communications and Electronic, January 1953, pp. 822-830.

